1. Field of the Invention
The present invention relates to an optical disc recycling method and a recycled optical disc.
2. Description of the Related Art
In the recent fields of data recording, research has been made for optical data recording and many optical recording methods are practically used. Because of many advantages, including non-contact recording and/or reproduction, recording density more than one level higher than the magnetic recording, and availability of various types of recording such as read-only, write-once and rewritable, the optical recording is conveniently used in a wide range of applications, from industrial to household.
The turnout of the optical discs such as compact discs (CD) and recordable compact discs (CD-R) has been increasing year after year, and with this increasing turnout of optical discs, unnecessary optical discs including used or unusable ones at the users and unaccepted ones at the factories have been increasing.
In the current circumstances, each of the users and manufacturers dispose such unnecessary optical discs. The optical disc is composed of a plurality of layers including a substrate of a light-transparent synthetic resin such as polycarbonate or the like, a reflecting layer of aluminum to reflect a light beam used for writing and/or reading an information signal, a protective layer of ultraviolet-curable-curable resin or the like, and a printed-label layer. So, the optical disc cannot be recycled or reused as it is. Most of those unnecessary optical discs are discarded, not recycled, which is not desirable for the standpoints of the global environment and effective utilization of natural resources.
There has been proposed an approach for recycling unnecessary optical discs, in which the unnecessary or discarded optical discs are crushed as they are and a mixture of the crushed substrate, and metal, protective and printed-label layer materials is used as a molding material. Also, there is another proposed approach. In the latter approach, the metal, protective and printed-label layers are removed from the substrate of the unnecessary optical disc by mechanical grinding or chemical treatment, and only the substrate is reused as a molding material.
There has been proposed an approach for recycling unnecessary optical discs, in which the unnecessary or discarded optical discs are crushed and a mixture of the crushed substrate, metal, protective and printed-label layer materials is used as a molding material. Also, there is another proposed approach. In the alternative approach, the metal, protective and printed-label layers are removed from the substrate of the unnecessary optical disc by mechanical grinding or chemical treatment, and only the substrate is reused as a molding material.
In the former method, the resulting mixture contains many impurities such as metallic material of the metal layer. Therefore, a product molded from the mixture will have unstable physical characteristics such as flexural strength or Young""s modulus in flexure. Thus, the mixture resulted by crushing the discarded optical disc can have only a limited application. When the chemical treatment is adopted, a large amount of chemicals has to be used, which will lead to a secondary contamination and give an adverse impact to the environment.
Further, in many write-once type optical discs such as CD-R, an expensive precious metal such as gold is used as the reflecting layer. In the latter one of the above methods, however, no consideration is actually given to recycling of such an expensive metal.
It is therefore an object of the present invention to overcome the above-mentioned drawbacks by providing an optical disc recycling method by which an unnecessary or unwanted optical disc can be recycled easily and inexpensively, and an optical disc renewed carrying out the optical disc recycling method.
The above object can be attained by providing an optical disc recycling method for an optical disc consisting of a substrate and at least a recording layer formed on the substrate, the method including, according to the present invention, steps of:
peeling off the recording layer from the substrate; and
bonding another substrate having a recording layer formed thereon to the substrate from which the recording layer has been removed, whereby a renewed optical disc is provided.
As in the above, the new substrate having the new recording layer formed thereon is bonded to the existing substrate of the optical disc, from which the old recording layer has been removed. Thus the renewed optical disc will have the new recording layer formed on the existing substrate thereof.
Also, the above object can be attained by providing an optical disc recycling method for an optical disc consisting of a substrate and at least a recording layer formed on the substrate, the method including, according to the present invention, steps of:
grinding at least one side of the optical disc substrate; and
bonding another substrate having a recording layer formed thereon to the ground side of the optical disc, whereby a renewed optical disc is provided.
As in the above, at least one side of the optical disc substrate on which at least the recording layer is formed is ground, and another substrate having a recording layer is bonded to the ground side of the existing substrate.
Thus, the new substrate having the new recording layer formed thereon is bonded to the ground side of the optical disc substrate. Therefore, the renewed optical disc will have the new recording layer formed on the existing substrate thereof.
Also, the above object can be attained by providing a recycled optical disc having a substrate from which a recording layer has been peeled off and to which another substrate having a recording layer formed thereon is bonded.
Since the above recycled optical disc still uses the substrate from which the recording layer has been removed, it is excellent in physical properties such as bending strength and Young""s modulus in flexure.
Also, the above object can be attained by providing a recycled optical disc having bonded to at least one ground side thereof another substrate having a recording layer formed thereon.
Since the above recycled optical disc still uses an optical disc of which at least one side is ground, it is excellent in physical properties such as bending strength and Young""s modulus in flexure.
These objects and other objects, features and advantages of the present intention will become more apparent from the following detailed description of the preferred embodiments of the present invention when taken in conjunction with the accompanying drawings.